Apparatus and method for blowing powder



Nov. 18, 1969 A. PFEIFFER ETAL APPARATUS AND METHOD FOR BLOWING POWDER Fil ed March 26, 1968 Fig.4

INVENTORS Albert Pfe/ffer Richard V. Cogswel/ Charles W. Lynch Herbert B. Kunerf BYAQ-M 7, 7. azww AQWJ uromvsrs United States Patent f 3,478,926 APPARATUS AND METHOD FOR BLOWING POWDER Albert Pfeiifer, Joppatowne, Richard V. Cogswell, Belcamp, Charles W. Lynch, Bel Air, and Herbert B. Kunert, White Marsh, Md., assignors to the United States of America as represented by the Secretary of the Army Filed Mar. 26, 1968, Ser. No. 717,488 Int. Cl. Bb 7/00; B67d 5/58, 5/54 US. Cl. 2221 21 Claims ABSTRACT OF THE DISCLOSURE Apparatus and method of operating for disseminating material in an aerosol cloud in the atmosphere comprising a base means, chamber means, gas inlet means, convergent-divergent nozzle means, conical shape means, knife edge means, and orifice means.

DEDICATORY CLAUSE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

Our invention relates to a powder disseminator to produce a fine, reproducible aerosol dispersed in the atmosphere to be utilized for crop dusting, riot control, etc.

Although the dissemination of dry powders in the atmosphere is regularly performed both commercially and militarily, the techniques and apparatus presently utilized have a number of problems associated with such utilization from the viewpoints of efficiency, mechanical complexity of disseminating devices, and reproducibility of the particle size. When the material to be disseminated is in powder form prior to dissemination, the powder agglomerates and compacts due to the effects of storage.

Such agglomeration, of course, results in the formation of lumps which resist effective pulverization and produces a particle size upon dissemination which is larger than desired. The production of particle sizes larger than desired results in an aerosol cloud which will settle rapidly and not cover a sufficient area to be effective.

A principal object of our invention is to provide a reliable disseminator means for material to produce a fine, reproducible aerosol of a narrow particle size range in the atmosphere.

A further object of our invention is to provide a means to produce a fine reproducible aerosol of a narrow particle size range in the atmosphere which is mechanically simple and provides an efiicient method of dissemination.

Other objects of our invention will be obvious or will appear from the specification hereinafter set forth.

FIGURE 1 is a plan view of our disseminator to be utilized for dissemination of material in tablet form.

FIGURE 2 is a sectional, assembled view of the device shown in FIGURE 1.

FIGURE 3 is an exploded view of the device shown in FIGURE 1.

FIGURE 4 is a sectional, assembled view of another embodiment of our invention for dissemination of material in powder form.

Our invention and FIGURES 1-4 will now be described in detail as follows:

The disseminator 1, as shown in FIGURE 1, comprises two significant parts; namely, base 9 and upper chamber 8, as shown in FIGURE 2. Chamber 8 is mated to base 9 by thread means 10 as shown in FIGURE 2. A washer means 11 is provided between chamber 8 and base 9 to provide an airtight seal between structures 8 3,478,926 Patented Nov. 18, 1969 and 9, as shown in FIGURE 2. Chamber 8, as shown in FIGURE 2, is shaped to contain a conical configuration recess 12 having sharp boundary edges 7. The edges must be maintained in a sharp condition in order to insure cylindrical symmetry of the base of the dispersed aerosol cloud. Mounted within chamber 8, as shown in all figures, is gas inlet 2 having a convergent-divergent shaped nozzle 5 within the chamber to impart supersonic velocity to the gas stream. A hole 13 of diameter is located in the top center of chamber 8, as shown in FIGURE 3, for the insertion therein of center post 3, as shown in FIGURE .2. Center post 3 has a tapered outer diameter 14 of and inner diameter 15 of as shown in FIGURE 3. The center post is assembled in base 9 by any convenient means, such as structure 16 having female thread means 18 and by male thread means 17, as shown in FIGURE 3. This mode of assembly is merely by way of example, and any conventional fastening means for the post can be utilized. When assembled, as shown in FIGURE 2, the insertion of the plug portion 19, as shown in FIGURE 3, of center post 3 in hole 13 forms an orifice 4, as shown in FIGURE 1.

The embodiment shown in FIGURE 4 is identical to the structure described above except that it has an elongated body 21 which is provided with a void 20 therein. Void 20 is closed at the end by base means 9, mated to body 21 by thread means 23.

To utilize the device shown in FIGURE 2, base 9 is removed from chamber 8; a compacted powder tablet is placed on surface 22, as shown in FIGURE 2, and within washer 11; and base 9 is reassembled to chamber 8. Gas inlet 2 is connected to any suitable gas supply, such as air or nitrogen; the only criterion being that the gas not be chemically reactive with the powder to be disseminated. The gas stream under pressure is then delivered to chamber 8 by means of nozzle 5 which imparts a supersonic velocity to the gas stream; the gas stream then produces a compression shock in the denser medium, the tablet, to produce fast and thorough grinding of the tablet in region 6 of the chamber. The powdergas stream swirls about center post 3 in cyclone fashion and the powder is expelled through orifice 4 as an aerosol cloud having a conical configuration with a symmetrical cylindrical base; the conical configuration being imparted by the configuration of cone shape 12 and the symmetrical cylindrical configuration by sharp knife edges 7. Orifice 4, if desired, can be provided with a nozzle means (not shown in the drawing) for aiming the direction of the aerosol cloud.

The embodiment shown in FIGURE 4 operates in the same manner as described above for the FIGURES l-3 embodiment. The only difference being that that material to be disseminated is placed in void 20 in powder form in FIGURE 4 as opposed to the tablet form above.

While we used 0.4 g. samples of material within cham her 8 to be disseminated and applied p.s.i. gas pressure for 575 m. sec., these values are representative only and are not critical. One can choose any suitable values for his particular needs.

It is obvious that other modifications can be made of our invention.

We claim:

1. An apparatus for disseminating an aerosol cloud in the atmosphere comprising a base means; chamber means mated to said base means; a washer means located between said base means and said chamber means to function as a seal means; gas inlet means located within said chamber means; convergent-divergent nozzle means located at the extremity of said gas inlet means which is within said chamber means; a conically shaped void within said chamber means, the boundary edges of said void being maintained as sharp knife edges; and an orifice means located in the top center of said chamber means.

2. The apparatus of claim 1 wherein said base means is mated to said chamber means by thread means.

3. The apparatus of claim 1 wherein said orifice means is formed by mounting a center post means in said base means and extending said center post means axially through said chamber means and terminating said center post means in a hole located in the top center of said chamber means, said post means providing an annular space between the post and the hole edges.

4. The apparatus of claim 1 wherein said base means is elongated.

5. The apparatus of claim 4 wherein said base means is void.

6. The apparatus of claim 5 wherein a cap means is mated to the end of said base means opposite to the end thereof mated to the chamber means.

7. The apparatus of claim 6 wherein said cap means is mated to said base means by thread means.

8. The apparatus of claim 1 wherein said orifice is provided with a nozzle means for aiming the direction of the aerosol cloud.

9. A method of disseminating an aerosol cloud in the atmosphere comprising the steps of providing a base means; placing material to be disseminated on said base means; providing a washer means on said base means; to function as a seal means; providing a gas inlet means into said chamber means; providing said gas inlet means with a convergent-divergent nozzle means located within said chamber means; providing a conically shaped void within said chamber means; providing the boundary edges of said void with sharp knife edges; providing said chamber means with an orifice means located in the top center of said chamber means; mating said chamber means to said base means; supplying gas means under pressure and having supersonic velocity to said chamber means through said gas inlet and nozzle means; grinding said material to be disseminated to a fine particle size by the gas means; and expelling the ground material through the orifice means as an aerosol cloud.

10. The method of claim 9 wherein the material to be disseminated is in compacted tablet form.

11. The method of claim 9 wherein said base means is elongated.

12. The method of claim 11 wherein said base means is void.

13. The method of claim 12 wherein the material to be disseminated is in powder form.

14. The method of claim 12 wherein a cap means is mated to the end of said base means opposite to the end thereof mated to the chamber means.

15. The method of claim 14 wherein said cap means is mated to said base means by thread means.

16. The method of claim 9 wherein said orifice is formed by mounting a center post means in said base means and extending said center post means axially through said chamber means and terminating said center post means in a hole provided in the top center of said chamber means, said post means providing an annular space between the post and the hole edges.

17. The method of claim 9 wherein said base means is mated to said chamber means by thread means.

18. The method of claim 9 wherein the gas means is any gas which will not chemically react with the material to be disseminated.

19. The method of claim 18 wherein the gas is selected from air and nitrogen.

20. The method of claim 9 wherein the gas is supplied under 100 p.s.i. for 575 m. sec.

21. The method of claim 9 wherein said orifice means is provided with a nozzle means for aiming the aerosol cloud.

References Cited UNITED STATES PATENTS 2,870,565 1/1959 Martin 222-193 3,276,627 10/ 1966 Birkestrand 222193 STANLEY H. TOLLBERG, Primary Examiner US. Cl. X.R. 

